Traditionally, if you’re running AutoHotkey and want to use the Program Files directory in a path, you’d use the built-in variable %A_ProgramFiles% which would parse out to wherever the directory was located. So, to open Putty (assuming it was installed) you’d have this code:

We run into trouble when we run a 64-bit operating system and a 64-bit AutoHotkey, as %A_ProgramFiles% then resolves to C:\Program Files but the PuTTY executable is actually located at C:\Program Files (x86)\PuTTY\putty.exe. I just so happened on this problem, and Google yielded a solution from this forum thread.